词法分析器设计实验报告

1、计算机与信息学院（信息工程系） 编译原理 实验报告专 业 班 级 12级计算机二班 学生姓名及学号 孙铭银2012217166 课程教学班号 计算机二班 任 课 教 师 李宏芒 实验指导教师 李宏芒 实验地点 计算机中心第四机房 2014 2015学年 第一学期实验一 词法分析器设计一、实验目的 通过本实验的编程实践，使学生了解词法分析的任务，掌握词法分析程序设计的原理和构造方法，使学生对编译的基本概念、原理和方法有完整的和清楚的理解，并能正确地、熟练地运用。 二、实验内容 用 VC+/VB/JAVA 语言实现对 C 语言子集的源程序进行词法分析。通过输入源程序从左到右对字符串进行扫描和分解，

2、依次输出各个单词的内部编码及单词符号自身值；若遇到错误则显示“Error”，然后跳过错误部分继续显示 ；同时进行标识符登记符号表的管理。 以下是实现词法分析设计的主要工作： （1）从源程序文件中读入字符。 （2）统计行数和列数用于错误单词的定位。 （3）删除空格类字符，包括回车、制表符空格。 （4）按拼写单词，并用（内码，属性）二元式表示。(属性值token 的机内表示) （5）如果发现错误则报告出错 7（6） 根据需要是否填写标识符表供以后各阶段使用。 三、实验流程图四、实验步骤1、根据流程图编写出各个模块的源程序代码上机调试。 2、 编制好源程序后，设计若干用例对系统进行全面的上机测试，并

3、通过所设计的词法分析程序；直至能够得到完全满意的结果。 3、 书写实验报告 ；实验报告正文的内容： 五、实验结果六、实验代码（C#）using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;namespace 词法分析器 /*单词符号 种别码 单词

4、符号 种别码 * if 1 标识符 40 * else 2 常量 41 * then 3 * 42 * while 4 / 43 * do 5 + 44 * begin 6 - 45 * end 7 > 46 * printf 8 < 47 * main 9 <> 48 * scanf 10 <= 49 * return 11 >= 50 * = 51 * ; 52 * ( 53 * ) 54 * 55 * 56 * + 57 * - 58 * 出错符 -1 * # 0 * */ public partial class Form1 : Form /* *成

5、员变量 */ String text = "" Char text_is;/输入流 int type_code=10;/单词种别码 int number;/整形常量 int line=1;/行号 int column = 1;/列号 char ch; int p = 0; String keyword=new String"if", "else","then", "while", "do", "begin","end","pr

6、intf","main","scanf","return" public Form1() InitializeComponent(); /* * 对输入流进行操作 */ private void readIo() text = "" try ch = text_isp+; catch (Exception) ; /*预处理*/ while (ch = ' ') ch = text_isp; p+; if (ch >= 'a' && ch <= &

7、#39;z') | (ch >= 'A' && ch <= 'Z') /标识符或变量名检测 while (ch >= '0' && ch <= '9') | (ch >= 'a' && ch <= 'z') | (ch >= 'A' && ch <= 'Z') text = text + ch; ch = text_isp+; p-; type_co

8、de = 40; for (int i = 0; i< keyword.Length; i+) /保留字检测 if (text=keywordi) type_code = i + 1; break; else if (ch >= '0' && ch <= '9') /数字检测 if (text_isp >= 'a' && text_isp <= 'z') | (text_isp >= 'A' && text_isp <= &#

9、39;Z') while (ch!=' '&&ch!=''&&ch!='#') text = text + ch; ch = text_isp+; type_code = -1; else number = 0; while (ch >= '0' && ch <= '9') number = number * 10 + ch - '0' ch = text_isp+; p-; type_code = 41; if (number &

10、gt; 32767) number = -1; else switch (ch) /其他字符 case '<':text=text+ch; ch = text_isp+; if (ch = '>') type_code = 48; text = text + ch; else if (ch = '=') type_code = 49; text = text + ch; else type_code = 47; p-; break; case '>': text = text + ch; ch = text_is

11、p+; if (ch = '=') type_code = 50; text = text + ch; else type_code= 46; p-; break; case '+': text = text + ch; ch = text_isp+; if (ch = '+') text = text + ch; ch = text_isp+; if(ch='+'|ch='-') text = text + ch; type_code = -1; else type_code = 57; p-; else typ

12、e_code = 44; p-; break; case '-': text = text + ch; ch = text_isp+; if (ch = '-') text = text + ch; ch = text_isp+; if (ch = '+' | ch = '-') text = text + ch; type_code = -1; else type_code = 58; p-; else type_code = 45; p-; break; case '*': type_code = 42; te

13、xt = ""+ch; break; case '/': type_code = 43; text = "" + ch; break; case '=': type_code = 51; text = "" + ch; break; case '': type_code = 52; text = "" + ch; break; case '(': type_code = 53; text = "" + ch; break; case

14、 ')': type_code = 54; text = "" + ch; break; case '': type_code = 55; text = "" + ch; break; case '': type_code = 56; text = "" + ch; break; case '#': type_code = 0; text = "" + ch; break; case 'n': type_code = -2; break

15、; case 'r': type_code = -3; break; default: type_code = -1; break; private void button1_Click(object sender, EventArgs e) String path = "" OpenFileDialog op = new OpenFileDialog(); if (op.ShowDialog() = DialogResult.OK) path = op.FileName; richTextBox1.Text = System.IO.File.ReadAll

16、Text(path, Encoding.Default); private String getTextIo() return richTextBox1.Text+'#' private void addData(String data1,String data2,String data3,String data4) try DataGridViewRow dgr = new DataGridViewRow(); DataGridViewTextBoxCell dt1 = new DataGridViewTextBoxCell(); DataGridViewTextBoxCel

17、l dt2 = new DataGridViewTextBoxCell(); DataGridViewTextBoxCell dt3 = new DataGridViewTextBoxCell(); DataGridViewTextBoxCell dt4 = new DataGridViewTextBoxCell(); dt1.Value = data1; dt2.Value = data2; dt3.Value = data3; dt4.Value = data4; dgr.Cells.Add(dt1); dgr.Cells.Add(dt2); dgr.Cells.Add(dt3); dgr

18、.Cells.Add(dt4); dataGridView1.Rows.Add(dgr); catch (Exception) ; private void button2_Click(object sender, EventArgs e) type_code = 10; p = 0; line = 1; column = 1; try dataGridView1.Rows.Clear(); catch (Exception) ; text_is = getTextIo().ToCharArray(); do readIo(); switch (type_code) case 41: addD

19、ata(number+"", "("+ type_code+ "," + number + ")","常量","("+line+","+column+")"); column+; break; case -1: addData(text + "", "(" + type_code + "," + text + ")", "有错误", &q

20、uot;(" + line + "," + column + ")"); column+; break; case -2:line+; column = 1; break; case -3: break; default: if(type_code>0&&type_code<40) addData(text + "", "(" + type_code + "," + text + ")", "保留字", "(

21、" + line + "," + column + ")"); column+; else if(type_code=40) addData(text + "", "(" + type_code + "," + text + ")", "标识符", "(" + line + "," + column + ")"); column+; else if(type_code>52&

22、;&type_code<57) addData(text + "", "(" + type_code + "," + text + ")", "定界符", "(" + line + "," + column + ")"); column+; else if(type_code=52) addData(text + "", "(" + type_code + ","

23、 + text + ")", "句尾符", "(" + line + "," + column + ")"); column+; else if (type_code = 0) addData(text + "", "(" + type_code + "," + text + ")", "结束符", "(" + line + "," + column + &

24、quot;)"); column+; else if (type_code >41&&type_code<52)|type_code=57|type_code=58) addData(text + "", "(" + type_code + "," + text + ")", "运算符", "(" + line + "," + column + ")"); column+; break; while

25、 (type_code!=0); private void Form1_Load(object sender, EventArgs e) private void richTextBox1_TextChanged(object sender, EventArgs e) 七、实验总结此次实验让我了解了如何设计、编制并调试词法分析程序，并加深了我对词法分析器原理的理解；熟悉了直接构造词法分析器的方法和相关原理，并学会使用C#语言直接编写词法分析器；同时更熟练的掌握用C#语言编写程序，实现一定的实际功能。实验二 LL(1)分析法一、实验目的 通过完成预测分析法的语法分析程序，了解预测分析法和递归子程

26、序法的区别和联系。使学生了解语法分析的功能，掌握语法分析程序设计的原理和构造方法，训练学生掌握开发应用程序的基本方法。有利于提高学生的专业素质，为培养适应社会多方面需要的能力。 二、实验内容 u 根据某一文法编制调试 LL （ 1 ）分析程序，以便对任意输入的符号串进行分析。 u 构造预测分析表，并利用分析表和一个栈来实现对上述程序设计语言的分析程序。 u 分析法的功能是利用 LL（1）控制程序根据显示栈栈顶内容、向前看符号以及 LL（1）分析表，对输入符号串自上而下的分析过程。 三、实验流程图四、实验步骤1、根据流程图编写出各个模块的源程序代码上机调试。 2、 编制好源程序后，设计若干用例对

27、系统进行全面的上机测试，并通过所设计的 LL(1)分析程序；直至能够得到完全满意的结果。 3、 书写实验报告 ；实验报告正文的内容：五、实验结果六、实验代码（C#）using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;namespace LL_

28、1_分析法 public partial class Form1 : Form public Production production; public char terminator;/终结符 public char nonterminal;/非终结符 public int flag = 0; public String Terminator = "" String STACK = ""/符号栈 String stack = ""/输入串 public struct Production public Char noter; pub

29、lic String production; /产生式结构体 public struct FIRST public Char noter; public String first; /FIRST集结构体 public struct FOLLOW public Char noter; public String follow; /FOLLOW集结构体 public struct PLACE public bool flag; public int x; public int y; public Form1() InitializeComponent(); private Char getNont

30、erminal(Char s) String nonterminal = "" for (int i = 0; i < s.Length; i+) if (si >= 'A' && si <= 'Z') if (!nonterminal.Contains(si) nonterminal = nonterminal + si; return nonterminal.ToCharArray(); private Char getTerminator(Char s) String terminator = &quo

31、t;" for (int i = 0; i < s.Length; i+) if (si >= 'a' && si <= 'z') | si = '(' | si = ')' | si = '+' | si = '-' | si = '*' | si = '/'|si='') if (!terminator.Contains(si) terminator = terminator + si; Terminat

32、or = terminator.Replace("", "") + '#' return terminator.ToCharArray(); private Production getProductions(Char s) int index = 0; Production productions=new Production20; for (int i = 0; i < s.Length - 1; i+) int flag = 0; if (nonterminal.Contains(si) && si + 1 =

33、 '$')/- productionsindex.noter = si; i = i + 3; while (si != ' '&&si!='n') if (flag = 0) duction =duction +si; i+; else productionsindex.noter = productionsindex - 1.noter; duction = duction + si; i+; if (si = '|') flag = 1; index+; i+; index+; return productions; /获取单一字符串 private String getSingleString(String s) String str = "" for (int i = 0; i < s.Length; i+) if (!str.Contains(si) str = str + si; re